The present invention relates to a semiconductor device.
There are many cases where highness or lowness of certain constant input voltage is compared with an other voltage in an analog circuit. It is common to use a differential pair in performing this comparison determination (i.e., see RAZAVI Behzad, “Design of Analog CMOS Integrated Circuits,” Chapter 4, October 2003).
When a voltage is put into a comparison in the differential pair, mismatch of the MOS transistors that constitute the differential pair causes an input offset voltage.
A characteristic of this input offset voltage depends on whether an operation region of the MOS transistors constituting the differential pair is the strong inversion region or the weak inversion region. The strong inversion region is a region where the MOS transistor is made to operate at high speed with a high consumption current, while the weak inversion region is a region where the MOS transistor is made to operate at low speed with a low consumption current.